(CNN) -- Dan Wallrath was honored as a Top 10 CNN Hero last year for his efforts to build mortgage-free homes for U.S. troops wounded in Iraq and Afghanistan.

He and his group, Operation Finally Home, recently partnered with the television show "Extreme Makeover: Home Edition" to build a house for Army Staff Sgt. Patrick Zeigler, who survived the 2009 shooting spree at Fort Hood, Texas.

CNN Heroes producer Kathleen Toner recently spoke to Wallrath about the experience, which will air on ABC on Sunday night.

Dan Wallrath: The biggest difference was just the magnitude of it. The first day when we had the Braveheart March, where volunteers and builders march in, that was very exciting -- getting things kicked off, just feeling the energy of all the volunteers and the folks.

And then this house was built in about 100 hours, where normally we take about six months. When you do it in a week, you see the impact of the whole community.

We had so many volunteers. It was amazing how smooth everything went. Of course on our other projects, we get to interact with the family a lot more during the construction. So we missed that. But the good part about working with the show is that the family has this amazing week where everything changes. So it's pretty exciting.

Toner: Building a house in 100 hours sounds almost impossible. How did it really work?

Wallrath: There were probably 4,000 or 5,000 volunteers involved, and it was a 24-hour work site. They set up floodlights and worked 'round the clock. They had to talk to the neighbors and let them know it's going to be going on 24/7, but the community was all for it.

What amazed me was that meant that people were volunteering at all hours. To volunteer from midnight until 4, 5 o'clock in the morning -- when the cameras and the celebrities are not there -- that's pretty special. I'd built homes for 30 years and never seen anything like that.

And we stayed ahead of schedule. I was impressed. They said that if we didn't exceed the record (for their shortest build time), we came real close.

Toner: What was the moment like when the family saw the home for the first time? Did you really say the show's signature line?

Wallrath: (laughs) We really did say, "Move that bus!" It was special. There were so many people there that day who'd helped out.

It was very exciting to see the look on the faces of the young couple. It's the same look I've seen so many times when we've given away homes before -- when the young man realizes that no matter what happens to them, his family is going to be taken care of. For him, going through everything he has, to see that burden being lifted off him, it was such a joy.

Toner: I hear you have plans for the empty lot next door to that home?

Wallrath: We had such a good response from the community (Salado, Texas, about 30 minutes from Fort Hood), so we felt like it was the right place to put another family. We spoke to the developer that we worked with, and he gave us that lot at a very discounted price. And we've found a great couple that's going to be in this house: another wounded veteran.

It'll just be great for them to have another veteran nearby. You and I can't relate to what they went through, but all of the guys tell me that when they have tough times, there's no substitute for talking to someone who's been through the same thing.

Toner: And you've established a fund where people can donate to help others wounded in the Fort Hood attack.

Wallrath: We're going to reach out to the other families that are all over the United States now. We're not going to be able to build homes for every one of them. But if they need wheelchair ramps, doors widened, a room added on -- that's the kind of thing that, as homebuilders, we're going to be able to do. It's so exciting to be part of it, because now all these families are not going to be forgotten. America's going to step up, and we're going to be able to help them.